Week 2 lecture for im2044 2012-2013

1. IM2044 – Week 2: Lecture
Dr. Andres Baravalle

2. Outline
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What is cognition?
What are users good and bad at?
Mental Models
Theories of cognition
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3. Interaction design
• The next slides are based on the
companion slides for the textbook
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4. What is cognition?
• Experiential cognition is a state of mind
in which we perceive, act and react to
events around us effectively and
effortlessly (Norman, 1993)
• Examples include driving a car, reading a
book or discussing
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5. What is cognition? (2)
• Reflective cognition involves thinking,
comparing and decision making
• Examples include learning, writing – and
your tutorial activities
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6. Cognitive processes
• Cognition can also be described in terms of
cognitive processes
• Examples include:
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Attention
Perception and recognition
Memory
Learning
Reading, speaking and listening
Problem-solving, planning, reasoning and decisionmaking
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7. Why do we need to understand
cognition?
• Interacting with technology is involves a number of
cognitive processes
• Need to take into account cognitive processes
involved and cognitive limitations of users
• Provides knowledge about what users can and cannot
be expected to do
• Identifies and explains the nature and causes of
problems users encounter
• Supply theories, modelling tools, guidance and
methods that can lead to the design of better interactive
products
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8. Attention
• Selecting things to concentrate on at a point in
time from the mass of stimuli around us
– Allows us to focus on information that is relevant to
what we are doing
– Involves audio and/or visual senses
– Enables us to be selective in terms of the mass of
stimuli but limits our ability to keep track of all events
• Information at the interface should be structured
to capture users’ attention appropriately, e.g. use
perceptual boundaries (windows), colour,
video/sound
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9. Activity: Find the price of a double
room at the Holiday Inn in Bradley
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10. Activity: Find the price for a double
room at the Quality Inn in Columbia
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11. Results
• Tullis (1987) found that the two screens
produced quite different results
– 1st screen - took an average of 5.5 seconds to search
– 2nd screen - took 3.2 seconds to search
• Why, since both displays have the same density
of information (31%)?
• Spacing
– In the 1st screen the information is bunched up together, making
it hard to search
– In the 2nd screen the characters are grouped into vertical
categories of information making it easier
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12. Multitasking and attention
• Is it possible to perform multiple tasks without
one or more of them being detrimentally
affected?
• Ophir et al (2009) compared heavy vs light multitaskers
– Heavy were more prone to being distracted than
those who infrequently multitask
– Heavy multi-taskers are easily distracted and find it
difficult to filter irrelevant information
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13. Design implications for attention
• Make information salient when it needs attending to
• Use techniques that make things stand out like colour,
ordering, spacing, underlining, sequencing and
animation
• Avoid cluttering the interface with too much information
• Avoid using too much because the software allows it
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14. Design implications for attention
(2)
• Overuse of graphics
Our Situation
 State
the bad news
 Be clear, don’t try to obscure the
situation
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15. Perception
• How information is acquired from the
environment and transformed into
experiences
• Vision is the most dominant sense for
sighted individuals
– Design representations that are readily
perceivable, e.g.
• Text should be legible
• Icons should be easy to distinguish and readable
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16. Is color contrast good? Find
italian
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17. Are borders and white space
better? Find french
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18. Activity
• Weller (2004) found people took less time to
locate items for information that was grouped
– using a border (2nd screen) compared with using
color contrast (1st screen)
• Some argue that too much white space on web
pages is detrimental to search
– Makes it hard to find information
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19. Which is easiest to read and
why?
What is the time?
What is the time?
What is the time?
What is the time?
What is the time?
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20. Design implications
• Icons should enable users to readily
distinguish their meaning
• Bordering and spacing are effective
visual ways of grouping information
• Text should be legible and distinguishable
from the background
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21. Memory
• Involves first encoding and then
retrieving knowledge
• We don’t remember everything - involves
filtering and processing what is attended
to
• Context is important in affecting our
memory (i.e. where, when)
• We recognize things much better than
being able to recall things
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22. Processing in memory
• Encoding is first stage of memory
– Determines which information is attended to
in the environment and how it is interpreted
• The more attention paid to something…
– The more it is processed in terms of thinking
about it and comparing it with other
knowledge…
– The more likely it is to be remembered
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23. Context is important
• Context affects the extent to which information
can be subsequently retrieved
• Sometimes it can be difficult for people to recall
information that was encoded in a different
context:
– “You are on a train and someone comes up to you and says
hello. You don’t recognize him for a few moments but then
realize it is one of your neighbors. You are only used to seeing
your neighbor in the hallway of your apartment block and seeing
him out of context makes him difficult to recognize initially”
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24. Recognition versus recall
• Command-based interfaces require users to
recall from memory a name from a possible set
of 100s
• GUIs provide visually-based options that users
need only browse through until they recognize
one
• Web browsers, MP3 players, etc., provide lists of
visited URLs, song titles etc., that support
recognition memory
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25. Personal information management
• Personal information management is a growing problem
for many users
– vast numbers of documents, images, music files, video clips,
emails, attachments, bookmarks, etc.,
– where and how to save them all, then remembering what they
were called and where to find them again
– naming most common means of encoding them
– but can be difficult to remember, especially when have 1000s
and 1000s
– How might such a process be facilitated taking into account
people’s memory abilities?
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26. Personal information
management
• Memory involves 2 processes
– Recall-directed and recognition-based scanning
• File management systems should be designed
to optimize both kinds of memory processes
– e.g. Search box and history list
• Help users encode files in richer ways
– Provide them with ways of saving files using colour,
flagging, image, flexible text, time stamping, etc
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27. Design implications
• Don’t overload users’ memories with
complicated procedures for carrying out tasks
• Design interfaces that promote recognition
rather than recall
• Provide users with various ways of encoding
information to help them remember
– e.g. categories, color, flagging, time stamping
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28. Learning in HCI
• Learning in HCI can be considered in
terms of:
– How to learn to use a computer-based
application
– Using a computer-based application to
understand a given topic
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29. Learning in HCI (2)
• People find it hard to learn by following
instructions in a manual
• prefer to learn by doing
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30. Design implications
• Design interfaces that encourage
exploration
• Design interfaces that constrain and
guide learners
• Dynamically link concepts and
representations to facilitate the learning of
complex material
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31. Reading, speaking, and
listening
• The ease with which people can read, listen, or
speak differs
– Many prefer listening to reading
– Reading can be quicker than speaking or listening
– Listening requires less cognitive effort than reading or
speaking
– Dyslexics have difficulties understanding and
recognizing written words
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32. Applications
• Speech-recognition systems allow users to interact with
them by using spoken commands
– e.g. Google Voice Search app
• Speech-output systems use artificially generated speech
• e.g. written-text-to-speech systems for the blind
• Natural-language systems enable users to type in
questions and give text-based responses
– e.g. Ask search engine
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33. Problem-solving, planning, reasoning
and decision-making
• They are all processes involving reflective cognition
– e.g. thinking about what to do, what the options are,
and the consequences
• Often involves conscious processes, discussion with
others (or oneself), and the use of artefacts
– e.g. maps, books, pen and paper
• May involve working through different scenarios and
deciding which is best option
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34. Cognitive frameworks
• Developed to explain and predict user
behaviour based on theories of cognition
• We will cover in the next pages some of
the models described on your textbook
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35. Mental models
• Users develop an understanding of a system through
learning about and using it
• Knowledge is sometimes described as a mental model:
– How to use the system (what to do next)
– What to do with unfamiliar systems or unexpected situations
(how the system works)
• People make inferences using mental models of how to
carry out tasks
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36. Mental models (2)
• Craik (1943) described mental models as:
– internal constructions of some aspect of the external
world enabling predictions to be made
• Involves unconscious and conscious processes
– images and analogies are activated
• Deep versus shallow models
– e.g. how to drive a car and how it works
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37. Gulfs of execution and
evaluation
• The ‘gulfs’ explicate the gaps that exist between
the user and the interface
• The gulf of execution
– the distance from the user to the physical system
• The gulf of evaluation
– the distance from the physical system to the user
• Bridging the gulfs can reduce cognitive effort
required to perform tasks
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Norman, 1986; Hutchins et al, 1986

38. Bridging the gulfs
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39. Limitations
• Based on modelling mental activities that
happen exclusively inside the head
• Do not adequately account for how people
interact with computers and other devices
in real world
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40. External cognition
• Concerned with explaining how we interact with external
representations (e.g. maps, notes, diagrams)
• What are the cognitive benefits and what processes
involved
• How they extend our cognition
• What computer-based representations can we develop
to help even more?
– Externalizing
– Computational offloading
– Annotating and cognitive tracing
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41. Externalizing to reduce memory
load
• Diaries, reminders, calendars, notes, shopping lists, todo lists
– written to remind us of what to do
• Post-its, piles, marked emails
– where placed indicates priority of what to do
• External representations:
– Remind us that we need to do something (e.g. to buy something
for mother’s day)
– Remind us of what to do (e.g. buy a card)
– Remind us when to do something (e.g. send a card by a certain
date)
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42. Computational offloading
• When a tool is used in conjunction with an external
representation to carry out a computation (e.g. pen and
paper)
• Try doing the two sums below (a) in your head, (b) on a
piece of paper and c) with a calculator.
– 234 x 456 =??
– CCXXXIIII x CCCCXXXXXVI = ???
• Which is easiest and why? Both are identical sums
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43. Annotation and cognitive tracing
• Annotation involves modifying existing representations
through making marks
– e.g. crossing off, ticking, underlining
• Cognitive tracing involves externally manipulating items
into different orders or structures
– e.g. playing Scrabble, playing cards
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44. Design implication
• Provide external representations at the interface
that reduce memory load and facilitate
computational offloading
e.g. Information
visualizations have
been designed to
allow people to make
sense and rapid
decisions about
masses of data
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45. Distributed cognition
• Concerned with the nature of cognitive
phenomena across individuals, artifacts, and
internal and external representations (Hutchins,
1995)
• Describes these in terms of propagation across
representational state
• Information is transformed through different
media (computers, displays, paper, heads)
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46. How it differs from information
processing
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47. 49

48. What’s involved
• The distributed problem-solving that takes place
• The role of verbal and non-verbal behavior
• The various coordinating mechanisms that are
used (e.g. rules, procedures)
• The communication that takes place as the
collaborative activity progresses
• How knowledge is shared and accessed
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49. Summary
• Cognition involves several processes including
attention, memory, perception and learning
• The way an interface is designed can greatly
affect how well users can perceive, attend, learn
and remember how to do their tasks
• Theoretical frameworks provide ways of
understanding how and why people interact with
products
• This can lead to thinking about how to design
better products
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